Fluoborate glass



1948- KUAN-HA-N, sum 2,456,033 7 Q 7 FLUOBORATE GLASS Z Sheos-Shet 1 Filed Feb. 9', 1946 INVENTOR ATTORNEY I Dec. 14, 1948. KUAN-HAN SUN FLUOBORATE GLASS 2 Sheets-Shet 2 Filed Feb. 9, 1946 KUAN-HAN SUN IN VEN TOR A TTORNE Y Patented Dec. 14., 1948 Kuan-Han Sun,

Eastman Kodak Company,

Rochester, N. Y., assignor to Rochester, N. Y., a

corporation of New Jersey Application February 9,1946, Serial No. 646,681

This invention relates to glasses having novel and desirable optical properties, and specifically to fluoborate glasses. Suchglasses have a refractive index which is higher for the same Abbe value (v) between 54 and 68, than any previously described glasses known to me.

While borate glasses containing fluoride have been reported in the literature, the amount of fluoride present has usually been small and has in almost every case been introduced as the fluoride of an alkali metal. The presence of jalkali fluoride in substantial quantities imparts to the glass optical properties which are inferior for lens design and for chemical and physical durability.

The fluoborate glasses herein disclosed contain little or no alkali, butcontain in combined form boron, oxygen lanthanum, and fluorine and one or more of the following metallic elementsz. beryllium, magnesium, calcium, zinc, strontium, cadmium, barium, divalent lead, silicon, titanium, thorium, columbium, and tantalum, with an atomic or ionic ratio of fluorine to boron up to about 1.3.

The general formula ofthese glassesmay be represented by the following notation:

MFr-ROv-BOLS in which We represents one or more of the fluorides of the above enumerated metals,;RO represents one or more of the oxides of the same metals.

Since Bezoa, LaaOa, TazO's, etc., are empirical formulas, it is equally expedient and more convenient, particularly in using cationic percentage or electropositive atomic percentage, to adopt the form 301.5, LaO1.s, TaO'2.5,,etc. In designating a glass batch,.it is convenient from the experimental point of view to indicate in weight percentages the actual individual constituents used. However, from the; theoretical point of view a fluoborate glass batch is better represented by the cationic percentage and the atomic or ionic ratio of fluorine toboron. The l cationic percentage or the electropositive atomic percentage is the same as. the mole percentage if all the molecular formulas of the fluorides and oxides are expressed in such a way that they contain only one metallic 'atom 'or' Although a glass maybe formed from a batch 11 Claims. (01. 106-47) tive and negitive ions (such as Ca++, La+++,

Th++, B+++, O- F, etc.), although the forces between adjacent atoms or ions are by no means purely ionic.

, It is apparent from the above discussion that,

in order to make a glass such as one of the calcium-lanthanum-fluoborate type, one could use containing the various ingredients'a's expressed in the batch formulas, these individual ingredients do not in fact exist assuchin the final product. It is more nearly correct to consider these glasses as an irregular aggregatao'f posi the combination of components indicated by any of the following systems: CaF2-LaO1.5-BO1.5; CaO-LaF3BO1.5; or

Similarly a glass made from LaFs and 301.5 with or without other ingredients, would contain also LaOrs and 3%.

In the following tables are given numerous examples of batch formulas yielding fluoborate glasses within the scope of my inventions and discoveries. In each of them the various components are given in both weight and cationic or mole percentages, the former being given under the letter W, and the latter under M. The fluorine to boron ratio, F/B, is also given for each example. Since the volatilization loss in most of the cases is slight, the compositions of the final glasses are not greatly diiierent from those of the batches from which they are produced. The refractive index for the D line, fi and the Abbe value, v, are also given.

The first'table includes examples of simple binary systems including lanthanum fluoride and boron oxide.

The second table gives eleven examples of the ternary system CaFz-LaO1.s-BO1.5:

Table I I Cal? LaO BO FIB 'n. v ample I i 5 1.5 D

11-1. 3 2. 6 59 24. 3 38 73. 2 0. 07 1. 7265 54. 8 11-2 11 10. 5 27. 4 29 62. 1 0. 34 1. 7191 55. 6 113 16 14. 7 54 23. 7 30 61. 6 0. 48 1. 6955 57. 4 11-4. 22 19. 3 47 19. 7 31 61. O O. 63 1. 6540 61. 0 11-5. 23 20. 1 46 19. 2 31 60. 7 0. 66 1. 6637 59. 5 11-6. 23 21. 4 50 22. 3 27 56. 3 0. 76 1. 6759 58. 0 11-7 24 21. 5 47 20. 2 29 58. 3 0. 74 1. 6823 56. 9 1I--8 24 23. 3 52 24. 3 24 52. 4 O. 89 1. 711 56. 5 I19 25 20. 4 4O 15. 7 35 64. 0 0. 64 1. 636 63. 0 11-10- 30 23. 9 35 13. 4 35 62. 7 0. 76 1. 6394 61. 6 I1-11 4O 26. O 12 3. 8 48 70. 2 0. 74 1. 6043 64. 5

e,4ue,oss 3 4 Figure 1 is a ternary diagram showing the re- Tab g1on of glass formation of the system exempli- 16 V fied in Table II in both Weight and cationic or mole per cent the former being shown in a Ex- LaFa 148101.11 BOlJi F/B 1m 1 sohcl llne and the latter in a broken line. These ample boundary hnes ale arbitary be z forma 6 8, A 40 16 4 D 76 8 O 27 1 7 43 56 8 ..1 pl .1 1 3 1 1 99E Q52 54'" 222 314 713 0.10 117,249 55.' 2 such as the S128 of the melt, race of cooling, shape 1 of the vessel and of the mold, temperatures of the melt during pouring, and temperature of the mold, but they serve to indicate the general region as observed experimentally. V

The third table gives two examples of the sys:

The sixth table gives a single example of the s stem ThF4'LaO1.5-BO1.5.

tem SIF2-L&O1.5-BO1.5. Table VI Table III, 1 I

ga ThFj 1421.015 301.5 F/B m) v Example SrFz LaOm 1301.5 F/B m) i g VIE-1.... 5.1 I 48 23.0 [32 72.0 0.28 I 1.7501 I 54.2 57 24 0 37 72.7 V 1 7.5 25 52.5 805 I has? is a tr i r'y e' kewing the i 2. 12 11 fl qf di 5 eeve e 1. esien 0 g a s f r n o t e 7 1 1 fi w Y eeilee 0.1 1 1 1 rablemyt m .e nser i s i ure' ein I e q ally ,eJtr ht." 25 PQFTLQQ fiBQW el r t le. ives seven examnles the f X. li F fla Que-B1 2 z l 'vl Table Iv I Exem- Example BaFa LaOm B011; F/B 1m v 131 9.- 355 73.2" BT05 1.1365 22.8 vii1;.1 ]'1l 11 9.311 5 53.2, 11- 4] 1636 in 31 68.1 0123 170451 56.6 33 70.2 0523' 1. 7062- 5613 s as 111 W V 1 21 5613' 8I7s' 120003 :"gf' The eighth table gives. three examples includ- 9 9 9. 1-0 1 34? ingxa. mixture of two fluorides with lanthanum anil heron oxides. 57. 9; HE

2 n B01} r B m) I 1 161 B8, a .032. 17008 T3515 21 6 3 2; 71 8 0:3 127400 54.9 25 0 30 0s 6 0.33 Figure 3; is a ternary diagram showing the The ninth table glves eight examples including Table IX o n s 1, Bali: LE0 T1101; f 130.; F/B 1 D 1 0.5 0.5 0.7 5 18.3 9. 32.0 000 10.0 27.2 03.0 020 1.722 55.2 0.5 0.5 0.8 0.5 20.2' 9. 20.0 6.8 2.0 30.0 68.0 0.29 1.7076 56.5 3:9 410 4,7 3.0 6.5 3. 13:0 2954 93019.2 68.0 0.29 1.7210 55.7 4.0 3:8v 5.0 8.0 Y 7,0 3. 1892 -l4 ;'0. 4.0- ,31;Q 67;9 0.29 l';7 O73; 56.5 7.0 0.3 8.0 4.5 17.0 6. 11.7 7,0 -1,9,34.0 ee.8 0.51 1.650 01.7 7.9 8:0 9:5 610 11.1" 5. 15.0 13.3 4.0 27.2 62.00.61 1.6776 58.7 7.8 8.0 10.7 7.0 10.7 5. 171:0 {12:95 4 .0 ;,24.9: 59.0 .062 21.8 16:00 4:41 2.0 3.1 1. 3,0 s 1.0 43.1 72.0 0.5; 1.630 being also pertinent here, Analogous charts The, tenth. tab includes two examples of ooulcl be made for the other ternary systems dislauthanunifiuoridewith boron oxide and an oxide closegi. qthenthanjauthanum.

11 mm; or tem LaF3LaO 1.s- BO1.s. pg 7 t Table XI Example LaF; ThFg L301 TiOa T1102 Chou Tao B01 5 FIB m) v 16 11.0 15 51.0 0.92 1. 8832 40.2 29 20.7 15 50.2 0. 57 1.8505 43.6 40 28.2 45.9 0.02 1.9048 31.8 42 27.8 40.5 0.00 1.9148 33.8 e 42 25.9 is 52.0 0.48 1.8902 35.3 37 25.9 16 52.4 0. 4s 1.886 39.0 40 30.8 17 53.3 0. 45 1.8544 43.4 45 32.0 15 49.9 0.60 1.8521 43.3

It is to be noticed that this group, while within Although the illustrative examples are prethe scope of my invention, is marked by a smaller dominantly simple cases, it is well known that percentage of boron oxide than those of the prethe introduction of small amounts of various comvious tables, a rather low percentage of fluoride, patible ingredients or constituents usually helps the presence of lanthanum and one or more of to prevent devitrification or other phase separatantalum, columbium, titanium, and thorium in tion and to increase chemical durability of the considerable quantities, and that they have a glass. A slight addition of other compounds value of n in the range between 1.85 and 1.92 and should not, therefore, be considered as a deviaof vbetween 30 and 45. 9 tion from this invention. Likewise, any com- Figure 4 is a chart on which refractive index, ponent may be partially or completely replaced n is plotted against Abbe value, 11. On account atomically by an equivalent amount of a chemiof their number, all the examples are not shown, cally similar component. The possibility of varibut a sufficient number are indicated by their ous combinations of compositions is, therefore, example numbers to show the approximate region enormous and is impossible to be covered in a A wherein they fall. For purposes of comparison, few examples. It is also to be noted that various the region for the most commonly available comsubstances or compounds may be used in the mercial glass is indicated by area B, that of fluobatch so that the final glass will contain the same phosphate glasses by area C, and rare-element amount of the ingredients originally intended. borate glasses by D. It is to be noted that the Although many fluorides may be used, the region A for the present glasses includes higher fluorides of calcium, strontium, barium, lann values for the corresponding 11 values in the thanum, and thorium are found to be'particuregion between 54 and 68 than any of the others. larly useful, The ease of melting the batches increases successively in batches containing, re-

It is to be further understood that the indicated spectively, C'aFz, SrFz, and BaFz; For batches boundaries of all these regions are approximate and not exact delimitations, and that the areas do containing lanthanum, thorium, and other oxides in fact somewhat overlap. the melting temperatures increase as the molec- It is to be noted that all the values of 1%, alular amounts of these oxides increase. The

high fluoride and boron oxide contents usually lower the melting temperatures.

though extending from 1.55 to 1.92, lie above a line passing through the points (4:70, n =1.50)

and (11:30, n =l.90) and defined by the equation In making these glasses, it is important that n =2.20.Olv, or r=220-l00 n fluorides are not introduced with batch materials The oup 0 glasses having a 11 Value between which give oil water vapor or other gases durin 68 and 54 are of particular value because their melting, since b ri acid, H 30 which gives on values of 11. are in most cases higher for the r large amount of water vapor on heating, is corresponding 1 value than those of any previous th common source for the boron oxide glass known to me. ponent, the melting of fiuoborate glasses may be Certain additio al pr p s for s m f the carried out in either of the following two ways: exampl s a given n l s XII a d XIII- In the first method, boric acid may be heated Ta le X gives e Partial dispersions between with other oxide components, such as lanthanum certain line of the Spectrum, and Table X111 oxide, etc., at a low temperature (about 250 C. iv s t pa dispersion ratios between for lanthanum oxide-boric acid mixture) to retain lines, for tWO W ve lengths: act for 10 or 20 hours so that all the water contents are driven away. The temperatures used should be as low as possible in order that the Table XII final product is not too hard to grind. The powder may be ground in a ball mill with flint balls. Proper amounts of fluorides are then introduced and well mixed. The mixture is melted down to a clear and fluid liquid in a platinum crucible or beaker at about 950-1250 C. L

The alternative and preferable method is to melt down, first, all the batch materials without fluorides. This usually can be done at about 1200-1300 C. A still higher temperature may be used to hasten the melting. Sometimes two layers of liquids may result. The fluorides are then added while the liquid layers are stirred with a platinum stirrer. The fluorides dissolve readily, and a uniform and clear liquid will result in a. short time. The temperature can then be. lowered somewhat. This method is preferable, because it does not involve the process of grinding of the oxide mixtures which may introduce impurities in the batch; and also because it provides a rapid means for fluorides to react with the oxide components to form a uniform and clear melt in a short time.

In. general, it: takes about one and one half hours to. melt down the oxide components of a 5.00-gram melt to fluid liquid or liquids at about 1250 C. I -he solution of fluorides takes about 10. minutes with stirring. The liquid glass is usually fluid at about 1200 C. At. this temperature the vol-atilization loss is. almost unnoticee able, However, it would be best to cover the melting not during melting. and stirring period. The glass can be poured after about one half ours stirring; at. somewhat. lower temperature. The, best molding temperatures are between 450- 650 6., though 550 C. would be suitable for .most cases. These glasses are colorless and durable against moisture attack.

Although valuable results are obtained When the percentage of fluoride. is small, it is to. be noted that in most of the examples given the cationicpercentage of fluoride is greater than 17, and this; is preferable, particularly when the system is a simple one, as in Tables; 1, VII, and X, and in most of the examples of Tables II, III, and IV. While the atomic ratio of fluorine to boron may be very small, as is shown for some of the examples, it lies in most cases, and preferably, between 0.4 and 1.3.

It is to be understood that numerous variations in proportions. and ingredients can be made within the scope of the claims. Forinstance, although Table X is given expressly for the purpose of showing examples Without lanthanum oxide as an original ingredient, it could be added to.-them.

When, inthe following claims, the expression fluoride selected from the fluorides is used, it does not mean afluoride, but includes one or several fluorides;

Having thus described my invention, what. I claimis:

1. A glass resulting from a batch comprising in. cationic percentage boron oxide, 45 to. 90 per cent; lanthanum oxide, 1' to. 28: per cent; and fluoride, 1 to 31 per cent, said glass having an no value greater than 2.2-0.01 v.

2. A glass resulting from a batch comprising oxide, 45 to 90 per 32 per cent; the

in cationic percentage boron cent; lanthanum oxide, 1 to boron and lanthanum oxides together totaling at least 50 per cent; and fluoride, 1 to 3-1 per cent; said glass having an m: value greater than 2.2-0.01 v.

3. A fluoborate glass resulting from a batch comprising in per cent by. weight boron. oxide, 15- to. 20 percent; lanthanum oxide, 15 to 50 per cent; at least one oxideselected from the oxides of; titanium, thorium, columbium, tantalum, 15 to- 30, per con-l and a fluoride of a non-alkali metal.

4. A flupborateglass. resulting from: a batch compris g. in. p r c nt by W i ht. ron ox de. 15 .to20 per. cent; lanthanum. oxide, 15 to5ilper cent tleastqos Qxide. s lec d m he xides oif titanium, thorium, columbium, tantalum, 15

to. 30 per cent; and a fluoride of a non-alkali metal, the atomic ratio of fluorine to boron being between 0.4 and 1.3,. and the glass having a value for no. greater than 2.20.0 1 r.

5. A fluoborate glass resulting from a batch comprising in per cent by weight boron oxide, 15 to 68 DGr cent; lanthanum oxide, 1 to 60 per cent; and fluoride; and having a value of no greater than 2.2-0.01 v.

6. Fluoborate glass having an Abbe value between 54 and 68 and a value for no greater than 2.2-0.01 1 and resulting from a batch comprising in per cent by- Weight boron oxide, 26 to 68 per cent; lanthanum oxide, 1 to 60 per cent; and fluoride over'3 per cent.

7. Fluoborate glass having an Abbe value between 54 and 68 and a value for no greater than 2.2-0,.01 1 and resulting from a batch comprising in per cent by weight, boron oxide, 20 to 53 per cent; lanthanum oxide, 7 to 60 per cent; and fluoride, 15 to 40 per cent.

8. Fluoborate glass having an Abbe value between 54 and 68 and a value for no greater than 2.2-0.01 11 and resulting from a. batch comprising in per cent by weight, boron oxide, 20 to 53 per cent; lanthanum oxide, 7 to 60 per cent; thorium oxide, 4 to. 31 per cent; and fluoride, 15 to 40 per cent.

9. Fluoborate glass having an Abbe value between 54 and 68 and a value for no greater than 2.2-0.01 1 and resulting from a batch comprising in per cent by welght,.boron oxide, 20 to 53 per cent; lanthanum oxide, 7 to 60 per cent; thorium oxide, 0 to 31 per cent; calcium fluoride, 0 to 40 per cent; strontium fluoride, 0 to 40 per cent; and barium fluoride, 0 to 50 per cent, the fluorides totaling 15' to 50 per cent.

10. Fluoloorate glass. having an Abbe value between 54 and 68 and a value for no greater than 2.2-0.01 1 and resulting from a batch comprising in cationic per cent, boron oxide (considered as B015), 56 to 81 per cent; lanthanum oxide (LaO1.5), 2 to 27 per cent; thorium oxide, 0 to 10 per cent; barium fluoride, O to 22 per cent; strontium fluoride, 0 to 17. per cent; calcium fluoride, 0 to 26 per cent, the fluorides totaling 1 to 26 per cent.

11. Fluoborate glass having an Abbe value be tween 54 and 68 and a value for no greater than 2.2-.-0.01 v and resulting from a batch. comprising in per centby weight, boron oxide, 20 to 65 per cent; lanthanum. oxide, 1 to 60 per cent; and fluoride, 1 to 60 per cent.

KUAN-HAN SUN.

REFERENCES CITED The following references are of record in the file; of' this; patent:

(Other. referencesonfollowing page).

Number FOREIGN PATENTS Number Country Date 8,704 Great Britain 1907 492,960 Great Britain 1938 OTHER REFERENCES Ser. No. 395,364, Berger et al. (A. P. C.), pub. May 11, 1943.

Certificate of Correction Patent No. 2,456,033. December 14, 1948. KUAN-HAN SUN It is hereby certified that errors appear in the printed spec'fication of the above numbered patent requiring correction as follows:

Column 2, line 38, Table I, last column thereof, for the indistinct numeral read 55.1 column 4, in the line preceding Table IX, and same column, in the paragrap following same Table IX, second and third lines thereof, for lauthanum rea lanthanum; column 5, Table XII, in the heading, for

read

same table, first column thereof, under Example, for 1-6 read I1 and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case 111 the Patent Oflice.

Signed and sealed this 10th day of May, A. D. 1949.

THOMAS F. MURPHY,

Assistant Gommtssz'oner of Patents. 

